9*10^8*3*10^5
2b=5^ $\sqrt{\Box}$7a
y2-x=5
2x-y=-7
y=-5/3x
3^2 * 4^(1/8)
8^2+x^2=(x+5)^2
f(x)=4x²-8x+4
8^2
x^2 + x + 5=-16
\begin{pmatrix}1&2\\ \:k&-1\end{pmatrix}X\begin{pmatrix}2\\ \:3\end{pmatrix}=\begin{pmatrix}8\\ \:15\end{pmatrix}\:find\:k